Engine starter



Nov. 9, 1937.

J. W. FlTZ GERALD ENGINE STARTER Filed May 24, 1937 2 Sheets-Sheet 1Nov. 9, 1937. J. w. FITZ GERALD 2,098,866

ENGINE STARTER Filed May 24, 1937 2 Sheets-Sheet 2 zz 631 M PatentedNov. 9, 1937 uslTED STATES PATENT-OFFICE ENGINE s'raarsn John W. FitzGerald, Milwaukee, Wis., assignor to Briggs &' Stratton Corporation,Milwaukee,

, Wis, a corporation of Delaware Application May 24, 1937, Serial No.144,347

25. Claims.

This invention relates to improvements in engine starters and refersparticularly to starters for automobile engines.

Like the copending application of John W. Fitz Gerald, Serial No.142,78'fi'flled-May 15th, 1937,

this invention has as its major object to provide an improvedconstruction for engine starters which entirely eliminates the use ofsprings and at the same time has all of the required flexibility andresiliency.

It is a special object of this invention to insure greater quietness andsmoothness of operation than has been possible. with starterconstructions heretofore in use.

Another object of this invention resides in the provision of an enginestarter wherein both endwise and torsional yieldability are attained bytransmitting the driving torque through a cushioning member of rubber.

Another object of this invention is to provide an engine starter of thecharacter described with a non-positive substantially self-energizingdriv- .ing' connection between the driven shaft and the pinion.

With the above and other objects in view which will appear as thedescription proceeds, thisinvention resides in the novel construction,combination and arrangement of parts substantially as hereinafterdescribed and more particularly defined by the appended claims, it beingunderstood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawings illustrate-several complete examples of thephysical. embodiment of the invention constructed in accordance with thebest modes so far devised for the practical application of theprinciples thereof, and in which: I

Figure 1 is a view partly in side elevation and partly in longitudinalsection, of an engine starter constructed in accordance with thisinvention;

Figure 2 is a view similar to Figure 1, but showing the manner in whichendwise yieldability is obtained;

Figure 3 is a view similar to Figure 1 illustrating the inanner in whichtorsional yieldability is obtained; I

Figure 4 is a perspective view of the rubber cushion member;

Figure 5 is a view similar toFigure 1 illustrating a slightly modifiedembodiment of the invention;

Figure 6 is a perspective view of the'rubber cushioning member and oneoLits associated ele- ElSSUEa Referring now particularly to theaccompanymg drawings in which like numerals indicate like partsthroughout the several views, the numeral 5 designates the ring gear ofan engine to be started, and the numeral 6 represents the startingmotor. The motor 6 has its shaft 1 extended past the ring gear to mounta pinion 8, which i is automatically. moved into mesh with the ringgearupon initial operation of the starting motor and disengagedtherefrom when the engine starts.

The pinion 8 is freely slidably mounted on the.

shaft 5 and has a sleeve 9 extended longitudinally therefrom. The outerend portion of the sleeve 9 is provided with threads l0 which engage thethreads H of a nut member I2.

Medially of its ends, the nut member carries a flange or disc l3 againstwhich one face of arubber block it abuts. The rubber block is in theform of a ring and its bore I5 is of a size to lit the diameter ofthenut member. Its thickness is greater than the length of the end portionof to normally extend beyond theend of the nut member.

'At its outer end, the shaftT has a collar l6 fixed thereto which isprovided with an annular the nut member upon which it is mounted so asflange I'I similar to the flange or disc l3 and arranged to abut theadjacent end face of the rubber cushion ring. J

. Engaged over the rubber ring I! and the flanges 13- and I1 is a shellor cover ring 18, the edges of which are flanged inwardly as at I! toengage over the flanges l3 andv I1 and hold the same.

against separation. I I a The space between the intumed flanges. i9 issuch that the rubber ring I4 is slightly compressed to establish, africtional driving connection between the shaft carried collar 16 andthe nut member sufliciently strong to cause the nut member to rotatewith the shaft during the initial period of operation of the motor 6.This rotation of the .nut member acting through its threaded connectionwith the.pinion"8 andby virtue of Figures 5 to 9, inclusive, may

the inertia of the pinion 8 propels the pinion forwardly toward the ringgear 5.

If the. forward advance, of the pinion is interrupted by an end to endengagement of its teeth with the teeth of the ring gear, as shown inFigure 2, the rubber ring is compressed slightly by reason of the factthat the nut member continuing to turn climbs out on the threads ill ofthe pinion which is momentarily held against ro tation. The shock ofimproper engagement is thus cushioned by the endwise resilience of therubber ring l4.

This condition of improper engagement, however, is but momentary for itrequires merely a slight turn of the pinion to effect proper engagement.The forward propulsion of the pinion thus continues until it abuts afixed stop collar 20 secured to the shaft 1.

Upon engagement of the pinion with this stop 20, its forward advancenecessarily stops and until the load of the engine is picked up androtation commences; the pinion, and consequently its screwill, arestationary, but the motor driven shaft 1 continues to revolve carryingwith it the nut member i2.

Continued rotation of the nut member i2 with the shaft 1 causes the nutmember to climb out on the threads of the screw thus further compressingthe cushion ring I4 and increasing the frictional driving engagementbetween its flange i 3 and one face of the rubber ring, and between theother face of the ring and the flange i1.

Endwise compression of the ring continues until the end of the nutmember abuts the face of the flange H, as shown in Figure 3, whereuponfurther endwise motion of the nut member is arrested, and if thebreak-away load of the engine has not been overcome, there being nopositive driving connection between the shaft 1 and the nut member, thetorsional yieldability of the rubber ring permits a relative twisting ortorsional motion between the flange l1 and the flange i3,

but without slippage between the faces of the rubber ring and theseflanges as the component of friction present at thesesurface to surfaceengagements after full compression of the rubber ring is suflicientlyhigh to exceed any normal engine loads.

After a certain amount of this relative twisting which is absorbed bythe rubber ring I, the break-away load of the engine is overcome androtation is imparted to the rin gear. In this manner, extreme quietnessof operation is insured as there is no sudden positive picking up of theload, and as the engagement of the nut member end with the flange i1 iscushioned by the compression of the rubber ring.

It is to be observed that the shell II beside serving as a protectingcovering, also holds the flanges l3 and i1 sufliciently close togetherto maintain the rubber ring ll under a slight degree of compression toinsure an initial driving connection between the two flanges necessaryto effect the forward propulsion of the pinion.

Properly constructed, this design is perfectly satisfactory, but topreclude the possibility of having the nut member bind on the threads ofthe screw, (it being noted that the nut member is not supported exceptby the screw), which condition might exist if in forming the inturnedflanges I! a slight twist were imparted to the nut member, any one ofthe constructions shown in be adopted. The modifled embodiments of theinvention, besides precluding the possibility of having the nut memberbind on the screw, also do not require as great a compression of therubber ring, as the drivingconnection is not dependent solely uponfrictional engagement, and consequently, the permitted endwise motionmay be-reduced which is desirable from the standpoint of quietoperation.

In many respects, the different embodiments of the inventionconstituting the modificationssl gwn in Figures 5 to 9, inclusive, areidentical with that shown in Figures 1 to 4, inclusive, but the initialdrive between the shaft and the nut -member is obtained differently.

The shell or covering, where it is used, serves principally as aprotection against dirt and grease, and otherwise merely holds theflanges between which the rubber ring is confined against too great aseparation.

One manner of obtaining the desired initial driving connection withoutthe initial compression of the rubber ring is through the provision of aplurality of tits 2| projecting from the opposite faces of the cushionring it and engaging in holes 22 in the flanges I3 and ll, as shown inFigures 5 and 6. This interengagement besides insuring rotation of thenut member with the shaft 1 to effect forward propulsion of the pinionduring initial operation of the starter, assures an adequate drivingconnection with little compression of the rubber ring and but a shortendwise motion of the nut member, which as stated, is an aid towardquiet operation.

Obviously, the relationship of the tits and the holes into which theyproject may be reversed as shown at 2i and at 22' in Figure 7, or ifdesired, the flanges l3 and I1 may be provided with radial ridges 23, asshown in Figure 8, to

' engage in cooperating radial grooves (not shown) be readily apparentto those skilled in the art,

that this invention provides anengine starter which embodies all of thedesired flexibility or resilience without the use of springs, and thatthe absence of a rigid unyielding driving connection with its permittedrelative torsional motion insures the optimum of quietness in operation.

While rubber has been found to be the most satisfactory material to usefor the ringer block which serves as the endwise and torsionallyresilient driving connection between the motor shaft and the pinion, itcan readily be appreciated that any other material having thecharacteristics of rubber may be employed. that must be present is bulkresiliency or cubical elasticity, and it is desirable that the materialbe nonmetallic. Hence, where the claims recite an elasticallycompressible material", it is understood that .only rubber or a materialhav- The characteristic ing the characteristics of rubber are conteinplated and that springsare definitely excluded.

What I claim as my invention is:

said members 'and arranged to impart an endwise and torsionallyyieldable. driving connection between said members entirely throughfrictional engagement of said members with the opposite 1 securely heldto said last named element and the member fixed-to the shaft toconstitute an endwise and torsionally resilient driving connectionbetween the shaft and the pinion. said coupling element being undercompression at all times.

3. In an engine starter of the character described including: amotordriven shaft and a pinion; means for drivingly connecting thepinion with the shaft including, two spaced cooperating members, one ofwhich is fixed to the shaft and the other connected with the pinion,said connection including threaded portions; and means for transmittingdriving torque at all times from the first to the second membercomprising, a rubber blockcompressed between said cooperating membersand transmitting driving torque from the first member to the rubberblock and from the rubberblock to the second member solely throughfrictional engagement between said members and the rubber block, v

4. In an engine starter: a power driven shaft; a pinion; an operativeconnection between the pinion and the shaft whereby endwise motion androtation is imparted to the pinion upon rotation of the shaft, saidconnection including a member having a connection with the pinion andfree from the shaft, said connection including threaded portions;another member fixed to the shaft; a solid body. of elasticallycompressible material having a high coefllcient of friction disposedbetween said members; and means for holding said members againstspreading with the body of elastically compressible material incompression therebetween so that said body provides a continuous drivingconnection between said members, said last named means imposing norestriction upon said members to movement together and rotarily-withrespect to each other so that said driving connection has a degree ofendwise and torsional resilience. v

5. In an engine starter: a power driven shaft; a pinion; a member havinga connection with the pinion, said connection includingthreadedportions; another member fixed to the shaft; and a mass of nonmetallicresilient material having a high coeflicient of friction interposedbetween said members and adapted through frictional engagement totransmit driving forcefrom one to the other, said mass constituting thesole driving connection between said members so that said members have adegree of rq fitiyeendwise and torsional movement?" v 6. In an enginestarter: a power driven shaft; a pinion freely slidable and rotatablethereon; a member having a connection with the pinion, said connectionincluding threaded portions; another member fixed to the shaft; a memberof solid compressible material having a high coeflicient of frictioninterposed between said members and adapted through frictionalengagement to transmit driving force from one to the other whileenabling relative endwise and torsional mo-.

tion between said members; and means for limiting endwise motion of saidmembers toward each other after a predetermined compression of saidsolid member.

7. An engine starter of the characterdescribed comprising: a powerdriven shaft; a pinion; a member connected with the pinion; saidconnection including threaded portions through a screw threadedconnection so pitched that rotation of said member with the shaft andrelative to the pinion eflects an endwise forward propulsion of thepinion, said member having a surface forming an abutment; another memberfixed to the shaft having a surface providing another abutment oppositethe first named abutment; and a member having cubical elasticitycompressible betweensaid abutments and'constituting the sole drivingconnection between the shaft and said member having the screw threadedconnection with the pinion.

8. In an engine starter for transmitting starting torque to the ringgear of an engine: a power driven shaft opposite the periphery of thering gear; a pinion freely rotatable on the shaft and.

between the shaft and said rubber member; and means for maintaining therubber member compressed, said means imposing no restraint upon therubber member to twisting or compressing further, and said rubber memberconstituting the sole driving connection between the shaft and themember having the threaded connection with the pinion so that shockincidental to misalignment of the pinion and ring gear and to thebreak-away load of the engine is resiliently absorbed by the rubbermember.

9. An engine starter comprising: a motor driven shaft; a pinion freelysliable and rotatable on the shaft; a threaded sleeve extending from thepinion; a nut member threaded on said sleeve; a flange carried by thenut member medially of its ends; a flange fixed to the shaft; and arubber ring fitted on the end portion of the nut member between itsflange and the shaft carried flange to provide a driving connectionbetween the shaft and the nut member, the thickness of said rubber ringbeing greater than the length of said end portion of the nut member tonormally withthe rubber ringcompressed therebetween pressed to provide asecure frictional connection between said member and the rubber memberand to' at all times provide a driving connection between the flanges,said last named means imposing no .restraint upon twisting or furthercompression of the rubber ring, and the rubber ring constituting thesole driving connection between the flanges so that endwise motion ofthe nut member toward the shaft carried flange, and relativecircumferential motion of said nut member and shaft is permitted.

10. In an engine starter: a motor driven shaft; a pinion freely slidableand rotatable on the shaft; a threaded sleeve connected with the pinion;a nut member mounted on the threaded sleeve; an annular flange carriedby the nut member medially of its ends; a flange fixed to the shaftoutwardly from one end of the nut member; a rubber ring encircling theend portion of the nut member between its flange and the shaft carriedflange and adapted to be compressed there-.

between to provide a non-positive endwise and torsionally resilientdriving connection between the shaft and nut member through frictionalengagement between the opposite ends of the rubber ring and saidflanges; and means for insuring the transmission of driving torque fromthe shaft to the nut member during the period of initial operation ofthe starter.

11. In an engine starter: a motor driven shaft; a pinion freely slidableand rotatable thereon; a threaded sleeve carried by the pinion; a nutmember threaded on the sleeve and having an an nular flange intermediateits ends; another flange fixed to the shaft; a rubber ring encirclingone end portion of the nut member and disposed between saidflanges, saidrubber ring having a normal thickness greater than the length of the nutmember end'portion which it encircles so as to space the adjacent end ofthe nut mem; ber from the shaft carried flange, said screw threadedconnection between the nut member and the pinion carried sleeveefi'ecting forward propulsion of the pinion upon rotation of the nutmember with the shaft and relative to the pinion and also causing thenut member to move toward the shaft carried flange upon any obstructionto the forward propulsion of the pinion so as to compress the rubberring between the flanges and effect a secure driving connection betweenthe shaft and nut member having a degree of endwise resiliency definedby the space between the shaft carried flange and the adjacent end ofthe nut member and having torsional resiliency to allow relativerotation between the nut member and shaft; and means to insure rotationof the nut member with the shaft during the initial period of operationof the starter.

12 In an engine starter: a power source; a

pinion automatically engageable with an engine.

part; and a non-positive self-energizingdriving connection between thepower source and .the pinion comprising, two abutments, one of which isconnected with the power source, and the other with the pinion; and ayieldable rubber cushion compressible between the abutments as the loadof the engine is picked up to form an endwise and torsionally yieldabledriving connection between said abutments which constitutes the soledrivingconnection between the power source and the pinion.

spaced endwise along the shaft; and a rubber ring encircling the shaftbetween said members with its opposite ends.engaging the members toprovide the sole driving connection therebetween.

14. In an engine starter: amotor driven shaft; a pinion free withrespect to the shaft; a member having. a connection with the pinion,said connection including threaded portions; another member flxed to theshaft, said members being spaced endwise along the shaft; a rubber ringencircling the shaft between said members with its opposite endsfrlctionally engaging the members and forming the sole drivingconnection therebetween; and means for limiting movement apart of saidmembers to maintain the rubber ring under compression.

15. In an engine starter: a motor driven shaft; a pinion free withrespect to the shaft; a member having a connection with the pinion, saidconnection including threaded portions; another member fixed to theshaft, said members being spaced endwise along the shaft; a rubber ringencircling the shaft between said members with its opposite endsengaging said members to constitute the sole driving connectiontherebetween; and interengaging means on the'opposite ends of the rubberring and said members to prevent relative rotation therebetween. I I

16. In an engine starter: a motor driven shaft; a pinion free withrespect to the shaft; a member having a connection with the pinion, saidconnection including threaded portions; another member fixed to theshaft, said members being spaced endwise along the shaft; a rubber ringencircling the shaft between said members; in-

terengaging means on the opposite ends of the rubberring and saidmembers; and a cover disposedover the rubber ring and said members andengaging the members to limit their relative movement apart and precludedetachment of the interengaging connections between the ring encirclingthe shaft between said members with its opposite ends cemented to themembers to provide the sole driving connection therebetween.

18. In an engine starter: a motor driven shaft;

a pinion loose on the shaft; a member also loose on the shaft and meansconnecting said member with the pinion so that relative rotation betweenthe pinion and said member causes relative endwise motion therebetween;another member fixed on the shaft and spaced endwise from said firstnamed member; a rubber ring encircling the shaft between said memberswith its ends engaging the same to provide the sole driving connectionbetween the members, said rubber ring being compressible endwise betweenthe members upon endwise motion of the first named member caused byrestraint of motion on the part of the pinion; and means for limitingthe compression of the rubber ring so that relative rotation between theshaft and pinion thereafter is absorbed by a torsional yielding of therubber ring.

19. In an engine starter: a motor driven shaft; a pinion free withrespect to the shaft; a member. having a connection with the pinion,said connection including threaded portions; another "pressedtherebetween, said cylindrical shell imendwise spaced along the shaft; aring of elas-v tically compressible material encircling the shaft;between said members with its opposite ends engaging the members toprovide the sole driving connection therebetween; and a cylindricalshell enclosing the ring and joined to said members to holdthe sametogether with the ring composing no restraint upon further compressionor twisting of the ring.

20. In an engine starter: a motor driven shaft; a pinion free withrespect to the shaft; a member having a connection with the pinion, saidconnection including threaded portions; another member fixed to theshaft, said members being spaced endwise along the shaft; a ring ofelastically compressible material encircling the shaft flanges on theopposite ends of the shell engaging said spaced members to hold the sametogether with said ring compressed therebetween,

said shell imposing no restraint upon further compression or twisting ofthe ring, and said ring being so shaped as to leave a space between itand an adjacent confining wall into which space the elasticallycompressible material flows upon further compression thereof.

21. In an engine starter: a motor driven shaft; a pinion free withrespect to the shaft; a member having a connection with the pinion, saidconnection including threaded portions; another member fixed to theshaft, said members being spaced endwise along the shaft; a ring ofelastically compressible material encircling the shaft between saidmembers to drivinglyconnect the same; a cylindrical shell enclosingithring; flanges on the opposite ends of the shell engaging said spacedmembers to hold the same together' with said ring compressedtherebetween, said shell imposing no restraint upon further compressionor twisting of the rin and said ring being formed with an annular grooveon its outside to provide a space between it and the shell into whichthe material of the ring flows upon further compression thereof.

22. In an engine starter: a motor driven shaft; a pinion free withrespect to the shaft; a member having a connection with the pinion, saidconnection including threaded portions; another member fixed to theshaft, said members being spaced endwise along the shaft and havingsurfaces providing opposed abutments; a ring of elastically compressiblematerial encircling the shaft between the abutments with the opposite 1ends thereof engaging the same to provide the sole driving connectionbetween said members;

which its mass may flow upon further compression of the ring. v

23. In an engine starter: a motor driven shaft; a pinion free withrespect to the shaft; a member having a connection with the pinion, saidconnection including threaded portions; another member fixed to theshaft, said members being spaced endwise'along the shaft; annularflanges of substantially the same diameter on said members; a ring ofelastically compressible material encircling the shaft between saidmembers with the opposite ends thereof engaging the flanges to'providethe sole driving connection between said members; a cylindrical shellengaged over the ring and said flanges; and inwardly directed marginaledge portions on the ends of the shell engaged over said flanges to holdthe same together with said ring compressed therebetween.

24. In an engine starter; a motor driven shaft; a pinion free withrespect to the shaft; a .memher having a connection ;with the pinion,said connection including threaded portions; another member fixed to theshaft, said members being spaced endwise along the shaft; a bushing ononeof said members projecting toward the other and engageable therewithto limit movement of said members toward each other said members havingopposed surfaces; a ring of elastically compressible material enc rclingthe bushing and having its ends engaged with said surfaces to providethe sole driving connection between saidone of said members projectingtoward the other joined to said members to hold the same together withthe ring of elastically compressible material compressed to an extent atwhich the end of the bushing is still spaced a distance from the othermember; the outer cylindrical surface of the bushing and the innercylindrical surface of the shell forming cylindrical walls and 00-operating with said opposed surfaces to define an enclosure for thering, and said ring being so shaped in cross section as to provide aspace between it and one of the cylindrical confining walls for thereception of the displaced mass incidental to further compression of thering.

JOHN W. FITZ GERALD.

